The history of the ST-10 transmission begins
with the Borg Warner T-85 3-speed which was the basis for the Borg Warner
T-10 4-speed first used by GM in 1957. Various versions of the T-10 were
used for AMC, GM and Ford. For a detailed history of the T-10 see classicar.com

The "second design"
ST-10 replaced the old T-10 and Muncie. GM started replacing Muncie
transmissions with the ST-10 starting around January-April 1974 depending on
the assembly plant. Design work was done by a Mr.
Johnson at the Borg-Warner Muncie, Indiana plant. Borg-Warner and GM
Chevrolet Division each had separate unrelated transmission plants in Muncie.

GM versions have a 26 spline input shaft
and most had a 32 spline TH400 output shaft (TH350 27 spline output shaft in
1982) and a 1" countershaft diameter.

Ford

AS1-T10

Short output shaft

Ford

AS2-T10

Long output shaft

GM

AS3-T10

For Corvette, F, and A bodies

AMC

AS4-T10

Long input shaft

Aftermarket for GM

AS9-T10

"Power Brute" with iron case and nickel gears

Borg-Warner also sold a version of this
transmission through speed shops under the "Power Brute" name. It had a 904
nodular iron case and 9310 Nickel alloy gears. The gears can be identified
by a small dimple drilled into the side of each gear. Most of these version
were designed primarily for drag racing and had a very low first gear. The
theory at the time was to use the low first gear to launch a car quickly.

Nearly all versions used in production vehicles from 1974-1979 had the
903 aluminum case. Sometime around late-1979 through 1981 versions were
offered in GM cars with the 904 nodular iron case. The change apparently
came due to increased warranty claims from stretching problems with the
aluminum case caused by the higher internal loading from the 3.42 first gear
ratio. These also had an iron midplate for added strength.

A 4+3 overdrive version by Doug Nash Engineering was used in the
1984-1988 Corvette.

I believe Borg-Warner sold the ST-10 design to Rockland Standard Gear in
the 1980's. It was then purchased by Richmond Gear which continues to
produce the ST-10 as an aftermarket transmission.

Service Tip: Examine the blocking ring and its
corresponding gear and check for proper clearance between gear and ring. You
want at least 0.50-inch. The two parts should face evenly without wobbling.
Use another blocking ring if your doesn't seat firmly.

Date
Codes The following information is for GM applications starting in 1974

Codes
are stamped on the driver's side of the case just to the rear for the side
cover.

Note
the difference between a STAMPED number and a CAST numbers.

For
a quick reference, the next to last digit identifies the year.

Position >>

1st

2nd

3rd and/or
4th

4th or 5th

Last digit

Meaning
>>

Warner
Gear Division

Month
"I" was skipped

Day of Month 1 or 2 digits

YearNext to last
digit

Production Shift

Codes >>

W

A = January

1 thru 31

4 = 1974

1

B = February

6 = 1976

2

C = March

5 = 1975

3

D = April

7 = 1977

E = May

8 = 1978

F = June

9 = 1979

G = July

0 = 1980

H = August

1 = 1981

J = September

2 = 1982

K = October

3 = 1983

L = November

4 = 1984

M = December

Example: WB2472 = Warner Gear, B =February, 24, 1977, 2nd shift

VIN Stamp

If the
transmission was originally installed in a car a partial VIN will probably
be stamped on the case.

VIN
information can be researched on the Internet.

The
partial VIN is usually stamped on the passenger-side boss shown in the
photo below.

The VIN
can be on top of the boss, on the side or both.

The VIN
is sometimes on the drivers side next to the date code per the
factory print above. This is usually the case with Corvette transmissions.

Not all
plant codes were used in all years.

New
models were usually introduced in late-summer fall and model production
usually ran from approximately August. thru the following August.
This means a car/transmission built in late 1976 is for a 1977 model year
car. The stamped VIN will match the model year of the car.

Example: 1BN100005 = Chevy, 1981, Norwood, 5th vehicle

Character Position: 1

2

3

4-9

Division

Year

Plant

Production No.

1

Chevrolet

0

1970

A

Lakewood,
NJ

Q

Detroit,
MI

2

Moraine,
OH 1982 up

Usually
starting with 100001 but may start with other numbers depending on vehicle
type and plant. For example, Corvette may start with 500001

2

Pontiac

1

1971

B

Baltimore, MD

R

Arlington, TX

2

Ste.
Therese, PQ

3

Oldsmobile

2

1972

C

Southgate, CA

S

St.
Louis, MO

3

Detroit,
MI

4

Buick

3

1973

D

Doraville, GA

T

Tarrytown, NY

3

St.
Eustache, PQ 1982 up

5

GMC Truck

4

1974

E

Linden,
NJ

U

Lordstown,
OH

4

Scarborough, ON

5

1979-up
GM Export

5

1975

F

Flint (Chev),
MI

V

Pontiac
(GMC), MI

4

Orion, MI
1982 up

6

Cadillac

6

1976

G

Framingham, MA

W

Willow
Run, MI

5

Memphis,
TN to 1975

7

GM of
Canada

7

1977

H

Flint
(Buick), MI

X

Fairfax,
KS

5

London,
ON 1979 up

8

GM Export

8

1978

J

Janesville, WI

Y

Wilmington, DE

5

Bowling
Green, KY 1981 up

9

GM Export

9

1979

K

Leeds, MO

Z

Fremont,
CA

6

Oklahoma
City, OK

0

GM Export

A

1980

L

Van Nuys,
CA

0

Pontiac
(GMC), MI

7

Lordstown,
OH

C

Chevrolet
Light Truck

B

1981

M

Lansing,
MI

1

Oshawa,
ON to 1977

8

Shreveport, LA

T

GMC Light
Truck

C

1982

N

Norwood,
OH

1

Oshawa,
ON or London, ON for 1978 truck

8

Fujisawa,
Japan

T

1979-up
GMC Caballero

D

1983

P

Pontiac,
MI

1

Oshawa,
ON 1979 up

9

Detroit,
MI

The
transmission below is for a 1981 Trans Am with the iron case, iron midplate and
3.42 1st gear.

Applications (a work in progress, please feel free to contribute)

There
is a 2 letter application code for GM transmissions used in
production.This was likely a paint stamp that quickly wore off.

Application codes are found in the GM master parts catalog.

All 2nd
design tailshaft housings are aluminum.

Warranty issues caused GM to use an iron case and midplate starting
around mid-1979 for some engines

Not all
79-up vehicles got the iron case and/or midplate, usually Trans Ams and
Z-28s.